This study aimed to determine the prevalence of human epidermal growth factor receptor 2 (HER2)–ultralow breast cancer among cases initially classified as HER2 immunohistochemistry (IHC) 0 and assess interobserver variability in interpreting low-level HER2 expression. Methods: In this multicenter retrospective study, all invasive breast cancer cases diagnosed between January and December 2022 across 10 Korean institutions were retrieved. Institutional pathologists reexamined HER2 IHC slides originally reported as IHC 0 according to the 2018 American Society of Clinical Oncology/College of American Pathologists guidelines and reclassified them as HER2-null (0), HER2-ultralow (0+), or HER2-low (1+). Slides from 10% of HER2-null and HER2-ultralow cases were digitized for central review and independently assessed by two pathologists, with discrepancies resolved by consensus. Results: Among 8,026 cases, 2,836 cases (35.5%) were initially reported as IHC 0. Upon re-review, 1,673 (59.0%), 1,139 (40.2%), and 24 (0.8%) cases were reclassified as HER2-null, HER2-ultralow, and HER2-low, respectively. The prevalence of HER2-ultralow breast cancer varied considerably across institutions (23.7%–78.1%). Central review of 268 digitized cases showed concordance in 193 cases (72.0%). Among the 75 discordant cases, 54 tumors (72.0%) were upgraded from HER2-null to HER2-ultralow, and 18 (24.0%) tumors were upgraded from HER2-ultralow to HER2-low. Furthermore, two tumors (2.7%) were downgraded from HER2-ultralow to HER2-null. Conclusions: Approximately 40% of cases initially categorized as IHC 0 were reclassified as HER2-ultralow. The substantial inter-institutional variability observed in interpreting low-level HER2 expression highlights the need for standardized training and quality assurance to ensure accurate identification of patients eligible for HER2-targeted antibody–drug conjugates.

Symmetric drug-related intertriginous and flexural exanthema (SDRIFE) is a rare drug-induced skin reaction characterized by distinctive rashes. It presents as sharply demarcated erythema in “V” shape on the flexural areas such as the buttocks and the groin. Additionally, it can affect other flexural regions such as the axillae, popliteal fossae, and antecubital fossae. SDRIFE typically occurs within a few days following systemic drug exposure, without prior cutaneous sensitization. It is generally associated with a favorable prognosis with no systemic involvement. Consequently, treatment usually involves discontinuation of the offending drug and symptomatic management with antihistamines, with systemic corticosteroids rarely necessary. Herein, we report a case of severe SDRIFE that developed six weeks after denosumab administration and required long-term systemic corticosteroids.

Heart failure (HF) is a major cause of mortality and morbidity in South Korea, imposing substantial physical, emotional, and financial burdens on patients and society. Despite the high burden of symptom and complex care needs of HF patients, palliative care and hospice services remain underutilized in South Korea due to cultural, institutional, and knowledge-related barriers. This position statement from the Korean Society of Heart Failure emphasizes the need for integrating palliative and hospice care into HF management to improve quality of life and support holistic care for patients and their families. By clarifying the role of palliative care in HF and proposing practical referral criteria, this position statement aims to bridge the gap between HF and palliative care services in South Korea, ultimately improving patient-centered outcomes and aligning treatment with the goals and values of HF patients.

Symmetric drug-related intertriginous and flexural exanthema (SDRIFE) is a rare drug-induced skin reaction characterized by distinctive rashes. It presents as sharply demarcated erythema in “V” shape on the flexural areas such as the buttocks and the groin. Additionally, it can affect other flexural regions such as the axillae, popliteal fossae, and antecubital fossae. SDRIFE typically occurs within a few days following systemic drug exposure, without prior cutaneous sensitization. It is generally associated with a favorable prognosis with no systemic involvement. Consequently, treatment usually involves discontinuation of the offending drug and symptomatic management with antihistamines, with systemic corticosteroids rarely necessary. Herein, we report a case of severe SDRIFE that developed six weeks after denosumab administration and required long-term systemic corticosteroids.

Symmetric drug-related intertriginous and flexural exanthema (SDRIFE) is a rare drug-induced skin reaction characterized by distinctive rashes. It presents as sharply demarcated erythema in “V” shape on the flexural areas such as the buttocks and the groin. Additionally, it can affect other flexural regions such as the axillae, popliteal fossae, and antecubital fossae. SDRIFE typically occurs within a few days following systemic drug exposure, without prior cutaneous sensitization. It is generally associated with a favorable prognosis with no systemic involvement. Consequently, treatment usually involves discontinuation of the offending drug and symptomatic management with antihistamines, with systemic corticosteroids rarely necessary. Herein, we report a case of severe SDRIFE that developed six weeks after denosumab administration and required long-term systemic corticosteroids.

Symmetric drug-related intertriginous and flexural exanthema (SDRIFE) is a rare drug-induced skin reaction characterized by distinctive rashes. It presents as sharply demarcated erythema in “V” shape on the flexural areas such as the buttocks and the groin. Additionally, it can affect other flexural regions such as the axillae, popliteal fossae, and antecubital fossae. SDRIFE typically occurs within a few days following systemic drug exposure, without prior cutaneous sensitization. It is generally associated with a favorable prognosis with no systemic involvement. Consequently, treatment usually involves discontinuation of the offending drug and symptomatic management with antihistamines, with systemic corticosteroids rarely necessary. Herein, we report a case of severe SDRIFE that developed six weeks after denosumab administration and required long-term systemic corticosteroids.

Symmetric drug-related intertriginous and flexural exanthema (SDRIFE) is a rare drug-induced skin reaction characterized by distinctive rashes. It presents as sharply demarcated erythema in “V” shape on the flexural areas such as the buttocks and the groin. Additionally, it can affect other flexural regions such as the axillae, popliteal fossae, and antecubital fossae. SDRIFE typically occurs within a few days following systemic drug exposure, without prior cutaneous sensitization. It is generally associated with a favorable prognosis with no systemic involvement. Consequently, treatment usually involves discontinuation of the offending drug and symptomatic management with antihistamines, with systemic corticosteroids rarely necessary. Herein, we report a case of severe SDRIFE that developed six weeks after denosumab administration and required long-term systemic corticosteroids.

Purpose: Notable effectiveness of trastuzumab deruxtecan in patients with human epidermal growth factor receptor 2 (HER2)–low advanced breast cancer (BC) has focused pathologists’ attention. We studied the incidence and clinicopathologic characteristics of HER2-low BC, and the effects of immunohistochemistry (IHC) associated factors on HER2 IHC results. Materials and Methods: The Breast Pathology Study Group of the Korean Society of Pathologists conducted a nationwide study using real-world data on HER2 status generated between January 2022 and December 2022. Information on HER2 IHC protocols at each participating institution was also collected. Results: Total 11,416 patients from 25 institutions included in this study. Of these patients, 40.7% (range, 6.0% to 76.3%) were classified as HER2-zero, 41.7% (range, 10.5% to 69.1%) as HER2-low, and 17.5% (range, 6.7% to 34.0%) as HER2-positive. HER2-low tumors were associated with positive estrogen receptor and progesterone receptor statuses (p < 0.001 and p < 0.001, respectively). Antigen retrieval times (≥ 36 minutes vs. < 36 minutes) and antibody incubation times (≥ 12 minutes vs. < 12 minutes) affected on the frequency of HER2 IHC 1+ BC at institutions using the PATHWAY HER2 (4B5) IHC assay and BenchMark XT or Ultra staining instruments. Furthermore, discordant results between core needle biopsy and subsequent resection specimen HER2 statuses were observed in 24.1% (787/3,259) of the patients. Conclusion The overall incidence of HER2-low BC in South Korea concurs with those reported in previously published studies. Significant inter-institutional differences in HER2 IHC protocols were observed, and it may have impact on HER2-low status. Thus, we recommend standardizing HER2 IHC conditions to ensure precise patient selection for targeted therapy.

Background/Aims: The programmed death 1 (PD-1)/programmed death-ligand 1 (PD-L1) pathway has not been fully evaluated in inflammatory bowel disease. We evaluated PD-1/PD-L1 levels in patients with ulcerative colitis (UC) and their significance in tonsil-derived mesenchymal stem cells (TMSCs) treatment. Methods: Using acute and chronic murine colitis model, we measured the PD-1 and PD-L1 levels in inflamed colonic tissues pre- and post-treatment with TMSCs. We also measured PD-1 and PD-L1 levels in colonic tissues from UC patients, compared to normal controls. Results: In the analysis using human colonic tissues, a significant increase in the levels of PD-1 and PD-L1 was observed in the colonic mucosa of patients with UC compared with normal controls (p < 0.001 and p = 0.005, respectively). When comparing the maximal disease extent, PD-L1 levels were highest in patients with proctitis (38.5 ± 46.7), followed by left-side colitis (17.5 ± 23.1) and extensive colitis (5.2 ± 8.2) (p < 0.001). In the chronic colitis model, the level of PD-L1 was decreased (p = 0.040) and the level of PD-1 increased more than in normal controls (p = 0.047). After treatment with TMSC, significant improvements were observed in body weight, disease activity index, and colon length recovery. Additionally, the levels of PD-1 and PD-L1 were recovered; PD-L1 significantly increased (p = 0.031), while the level of PD-1 decreased (p = 0.310). Conclusions The altered expression of PD-1 and PD-L1 in colonic mucosa may be a possible mechanism of UC, and T-MSC-derived PD-L1 could help suppress colitis.

Immunoglobulin G4-related disease (IgG4-RD) can involve multiple sites throughout the body. The most commonly affected sites in the head and neck are the salivary and lacrimal glands, respectively. Very few cases of IgG4-RD manifesting in the tonsils have been reported. Herein, we report the imaging findings of a 49-year-old female with pathologically confirmed IgG4-RD after a right-side tonsillectomy. The lesion showed diffuse homogeneous enhancement and appeared isointense and slightly hyperintense on T1- and T2-weighted magnetic resonance imaging, respectively. Diffusion restriction was also observed, which was considered to be due to the large number of IgG4-rich plasmacytes, and could vary depending on the degree of fibrosis. As distinguishing IgG4-RD from other diseases based solely on imaging is challenging, it is important to consider differential diagnosis, and clinical considerations are essential.